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bluebird boxes: be a good landlord

THE NEIGHBOR WHO HANGS BAGS of giant homegrown shallots on my gate also has rules and regulations. “Bluebird Rules and Regulations,” to be specific, as in: How to be a good bluebird landlord, minimizing hazards for the beloved birds with specific nestbox tips and tricks.

Deb's bluebird houses in fieldDeb, my “next-door” neighbor despite the uphill mile of dirt road between us, installed her first nestbox 17 years ago. Today, she has a trail of 24 boxes on her farm in Columbia County, New York, where she spends much of bluebird season (here, that’s March through August) “worrying over my little charges,” she says.

guard for bluebird boxq&a: deb’s bluebird rules and regulations

Q. Where did you learn to be a good bluebird landlord?

A. I rely heavily on Bet Zimmerman’s website Sialis.org and a wonderful little pamphlet called “Enjoying Bluebirds More” by Julie Zickefoose, and I always urge (implore, really) people interested in putting up nestboxes to read Bet’s page of bottom-line advice for new bluebirders. [Note: Sialia sialis is Latin name for the bluebird’s genus and species.]

Q. So what’s the basic thrust of your Bluebird Rules and Regulations? 

A. My boxes are installed to encourage successful nesting by the bluebirds by minimizing the many threats they face throughout their season. Before nesting season even begins, I make sure my boxes are cleaned from the previous season.

I also apply a coat of Ivory soap to the ceiling to prevent wasps’ nests, and I attach a bit of plastic netting to the inside of the box opening to serve as a “kerf” (a little ladder that fledging bluebirds can climb to reach the exit hole, photo below).

kerf for bluebirdsThen I do a little dance to bring good luck because, well, you never know.  Last week, as I was rubbing Ivory soap on the ceilings of my 24 boxes, I was thinking how amazing it is that these beautiful creatures survive at all considering the many threats they face while nesting.  Here are a few:

  • Aforementioned wasps’ nests;
  • Blowfly larvae who feed on nestlings during prolonged rains or drought;
  • Raccoons, snakes and rats who steal eggs and kill nestlings;
  • Cats who stalk;
  • Competition from tree swallows and wrens;
  • Nestlings that are unable to climb out of the box at fledging time (necessitating those “kerfs” I mentioned earlier);
  • And most dire of all, the dastardly house sparrow.

Q. What’s the key to success, if there is one? Sounds like a lot of possible trouble can occur. 

A. The most important advice I can offer is to use a nestbox specifically designed for bluebirds, locate it properly and monitor it throughout the nesting season. [Get Cornell NestWatch’s plans for bluebird and other species-specific bird boxes.]

Spring comes, we hear that cheerful throaty song and we are moved to put up a home for the bluebird.  We rush to buy a birdhouse, nail it to a fence post and think we have done a good deed for the bluebirds. If your readers take away only one idea it is this: An improperly located and unmonitored nestbox will quickly become a bluebird death trap.

Q. How do we avoid that?  

A. Bluebird Rule #1:  Resist all temptation to hammer a box onto the nearest tree, the side of a building or fence post. Doing so will almost certainly bring disaster to the bluebirds and heartache to you.

A raccoon, rat or snake can easily climb that wooden post to steal eggs and kill nestlings. Instead, your nestbox should ideally be mounted on conduit pipe that a raccoon can’t easily climb, fitted below with a baffle or predator guard (photo below; predator guards can be made from stove pipe) and located in an open, grassy area at least 100 feet away from shrubs or other natural “cover.”  Nestboxes should face away from prevailing winds, which generally means facing south. If you are lucky enough to have tree swallows, you will want to have a pair of nestboxes, back to back, about 15 to 25 feet apart (like in the top photo).

guard 2 for bluebird houseThen, follow Bluebird Rule #2: Do everything possible to prevent house sparrows from invading. Bet Zimmerman says on her website, “Successful bluebird landlords do not tolerate house sparrows…which are non-native nest site competitors. In my opinion, it is better to have no nestbox at all than to allow house sparrows to breed in one.”

I agree and I think it bears repeating: It is better to have no nestbox at all than to put one up where there are house sparrows, which are invasive alien predators and one of only a few bird species that are not protected by the Migratory Bird Act of 1918. (The European starling is another species not protected by this Federal law, but it is too big to fit into the entry hole of a properly sized bluebird nestbox. The house sparrow, on the other hand, is smaller than a bluebird and can easily fly into the box.)

Q. What are signs of house sparrow invasion?  

A. The first is a trashy-looking nest that includes weeds, straw, and garbage in a big arc curving up the back of the box. The second–and most disturbing–sign is a dead bluebird inside the box. If you find a dead bird inside the box, chances are very, very high that it was trapped and killed by a marauding house sparrow. Bet recommends a number of ways to manage house sparrows.

Q. So besides proper siting, the right box, and reckoning with house sparrows, what other care is essential to being a good landlord?

A. Bluebird Rule #3: Once erected, monitor your nestbox. To quote from “Enjoying Bluebirds More:”

“A bluebird box put up and never monitored is like a letter never sent.”

In addition to monitoring for house sparrows, I also watch for blowfly larvae, which suck on nestlings during prolonged periods of stressful weather conditions like drought or rain. I even keep a spare dry nest on hand to swap out if a nest gets wet or infested (but I admit I do not recommend this for the inexperienced bluebirder).

sparrow spooker 2I also watch very carefully for the first bluebird egg. Once that first egg has been laid, nothing will keep the female out of the nestbox, so that is when I put up a sparrow spooker (above and below)–basically a stick with lots of reflective streamers hanging off it. The flapping, blowing streamers scare the house sparrows and deters them from entering. (If I were to put up the sparrow spooker before the bluebird lays her first egg, she too would be deterred from using the box, so I only put it up after that first egg is laid.) Really good instructions for making a sparrow spooker are here.

sparrow spookerQ. Beyond the box regimen, are there other rules we need to follow?

A. The last (but not least) important advice I have is really up your alley, Margaret, and that is to create a backyard paradise by planning and planting for bluebirds.

To quote again from “Enjoying Bluebirds More:”  “What use is a bedroom if there is no kitchen?”

Bluebirds, like all other wild species, are under increasing pressure from habitat loss. Planting fruiting trees and shrubs helps the bluebirds thrive year-round. Because bluebirds have a fondness for ground-hugging prey, every time we mow our lawn, we create ideal foraging conditions for bluebirds. Water is also a great lure for bluebirds who love to bathe, even daily.

Q. Any last words?

A. Nothing makes me happier than seeing fledglings leave the box for the first time. I wish all of your readers great success in their careers as bluebird landlords. And, may all your blues be birds!

extra: why are bluebirds blue?

WHY ARE bluebirds blue? The obvious answer seems to be, “Because they have blue feathers,” but that’s not it, says a segment on the public-radio show BirdNote. It’s all about the feathers’ structure—and the light trick they create right before our eyes. Listen in to learn what’s going on. (Photo by Joanne Kamo courtesy of BirdNote.)

(All other photos except bluebird, above, and top photo of dirty box by my neighbor Deb, used with permission.)

  1. Shirley Halverson says:

    I have native Douglas squirrels that take over just about every nest box I have. They climb metal pipe up & down like they have velcro feet. If I put a box under eaves of a shed, they just climb the siding. They enlarge the birdhouse holes & fill the boxes with insulation & leaves. I’ve put metal barriers around the holes and they can’t get in, but still harass nesting birds. Sometimes they just make another hole between the roof & side of the box to get around the one I alter. I try to be a backyard wildlife sanctuary, but these squirrels are making me say “Uncle”. (Washington State)

    1. margaret says:

      Hi, Shirley. I have to admit I am not much of a squirrel lover! What wild monkeys they are, and so clever. The important things for the birds (as well as to keep squirrels out) is never to put boxes on trees or buildings, but rather on regulation poles with the serious baffles like in the photo, and out in the open. Sounds like you would need metal poles. I do find that boxes on poles out in the open and with the proper metal baffle defeat them.

  2. Joe Doran says:

    I have used the baffle on a wooden pole for five years and have yet to see a squirrel get by it and it is a bird feeder. I have watched two squirrels , tails flipping, scratch themselves in frustration. It is about half the length of your pictured. A bit longer than a large juice can which I purchased at a bird supply store.

  3. Shawn says:

    It’s also important to have a tree or shrub about 10 to 15 feet away from bluebird boxes. These provide a landing pad as it were for fledglings leaving the nest. The boxes in the photos above are not located properly — they’re WAY too far away from nearby trees.

    1. Ellen B says:

      Shawn, aren’t those two boxes a bit too close together, too? Thanks for the info. And Margaret and Deb, a HUGE thanks for the article!

      1. margaret says:

        Both Sialis.org and Cornell Nest Watch say open areas, and like 300 feet from scrubby brushy vegetation that attracts the dreaded house sparrows. However that’s for our Eastern species — the Western bluebirds does NOT want open areas like that, Sialis clarifies. Sialis says paired boxes can be 5-20 feet apart (some references even say on same pole, back to back).

        I can tell you Deb is overrun with bluebird pairs every year, and every other box is tree swallows…so the open location (though there are some phone wires nearby that you see them perch on, and there are trees not too far.

  4. Chris says:

    Diatomaceous Earth (must say food grade on label, industrial grade for pools has poison added) can be spread in nest boxes under nest or even sprinkled into nests to get rid of and prevent blowfly larvae. Safe for birds and even healthy for them. Farmers use it a lot to help control wetness and keep out or remove bugs in feed, bedding and even applied directly on animals. It will dehydrate/kill any bug, worm or larvae that comes in contact with it. Using it ahead of time in nest boxes helps prevent wetness and keeps larvae from even forming. D.E. is also used in kitty litter for clumping since it absorbs wetness. Often fed to animals and chickens to remove internal parasites of all kinds. High in healthy minerals and silica. Just make sure to use food grade only. Available at feed stores and health food stores as well as online.

  5. Roger Bergold says:

    I have had nesting bluebirds for several years. They are here all year round. I would like to clean out or even replace their house. It has been in the same spot for over a decade. Can I replace it now, without fear of damage to the birds?

    PS made every mistake when I put the nesting box up. It faces north and is near a big oak tree. Yet, the blue birds seem to thrive. In fact, I have seen at least four of them together near the box.

    I would appreciate your advice. Thanks

    1. margaret says:

      Hi, Roger. I’d clean it right away, yes. If you plan to put a new house up, just have it ready to go so there is now “down time” I guess. Lucky you!

  6. Jennifer Bertke says:

    Thank you for sharing your knowledge on bluebirding. I’m hooked and have referred to Bet’s site a great deal! I’d love to hear your thoughts on the following dilemma . . . morning time comes and a pair of bluebirds feed and sit on my box. The female pokes her head in the box and jumps in every few minutes. By the afternoon the bluebirds are gone and the HOSP is sitting on top of the box. They eventually hop in the box. I’ve read it’s too early for a sparrow spooker since the bluebirds haven’t laid any eggs yet. Help! I’m losing sleep!

    1. margaret says:

      Sorry to miss this question till now, Jennifer. I just don’t know how one sorts out the birds wars; I watch the swallows and bluebirds duke it out in my garden every year, and don’t intervene. The Sialis website had some other recommendations, including using monofilament early — those ideas are at this link.

    2. karen says:

      Jennifer, order the Van Ert trap (on-line) and don’t be afraid to use it! Once set, check it every 15 minutes (I once trapped a bluebird by accident, he was okay but stunned). After you capture a HOSP, place a large clear plastic bag over the top of the box then open it. The HOSP will fly to the top of the bag, but be careful. They are sneaky and can find an opening in the bag if you let them. Dispose of them. Do NOT let them go. http://www.sialis.org/hospdispatch.htm One of my nest boxes seems to attract HOSP to it, so that is my trap. Good luck!

  7. Julie says:

    We just put our bluebird boxes away for the winter. In one of them there was no nest but 3 dead martens (birds). Do you know what could have happened? My husband built the box from a proper bluebird box pattern he found online. Thank you.

    1. Bill in Parker, Colorado says:

      Hi Julie,

      I had a similar thing happen several years ago. I had a Barn Swallow die in a blue bird nest box. Broke my heart to find it there.

      Barn Swallows have very weak leg muscles. They can not jump like blue birds do. There for they get trapped in a blue bird house and die. In my houses I have cut grooves in the wood on the inside below the entrance hole. This gives the Barn Swallows and Tree Swallows a ladder to climb up to get to the hole. I have not had any more dead swallows in a nest box.

      Best Regards,
      Bill

  8. Helen Allen says:

    Hello, I live in Maine and the first blue birds were here in Old Orchard Beach Maine. 5 years ago, I was 72 and never saw a blue bird before. So excited I went out and bought 2 blue bird houses. Nothing for 2 years. the birds were still around so I got some meal worms and then saw a male and female building a nest in a old yucky bird house that was hanging in a fir tree 15 ft away from my house. They have had babies every year since and still using the same old bird house. I now have feeders I stuck to my kitchen window. Plastic ones so I can watch them every day. The delight of my life.
    . .

  9. Dianne says:

    What a timely article as I saw Mom and Pop Bluebird checking out the real estate in our yard a few days ago. Now loaded with all this information, I promise to be a better landlady this year. Although we don’t have a large open area we did have a family occupy the house last year (our first year). Thanks for the information Margaret.

  10. Linda B says:

    Well, it is St Patties Day here in the St Louis area, and about 2 weeks ago we had a Mom & Dad Bluebird and 2 young ones show up at our feeder. I was shocked. Never have seen them here in 25 years. Fellow at the feed store said they could eat the hulled sunflower seeds, so I got some and put out. They have visited every day. Seems like very early for them to have had babies, and maybe their normal food is still frozen? It would be tempting to put out boxes, but we have backyard chickens, and our area is regularly patrolled by Red Tailed Hawks. I don’t even let Robins put up a nest on our downspout angle places any longer…the hawks just wait until the babies are big enough to fly, then come in and carry them off. Trying to keep lots of hedgerow area going so there is some better protection. Sigh.

  11. Jacki says:

    The one predator not mentioned is the two legged kind. Someone did a lot of research and installed several bluebird boxes around a little local lake (which seemed correctly constructed and placed) only to have a human come along and destroy them, after they had been inhabited. The nest boxes have been removed now. How sad is that?

  12. Marie Cooney says:

    I enjoyed the article except for the demonizing of others species. Simply a case of a human not understanding nature, and uncalled for.
    This is what I observe in my yard;
    I love blue birds and have watched for 5 years now as the male blue visits the sparrow nests first, ( slight harassment)
    After the sparrow babies are old enough, they turn to food begging from the blue birds , then to being the aggressors. That’s when I might step in, or not.
    I love all animals. Life is harsh on all of them, yet I only see through a small human scope, so what do we really know?
    After all, the human being is the great wrecker of this Earth, not the lowliest sparrow.

    1. margaret says:

      Hi, Marie. The house sparrow, being a non-native species, is a good example of what happens when an organism accidentally gets introduced to a new environment where it becomes dominant because the natural predators from its homeland don’t exist. It’s not my neighbor’s or my demonizing them, but just the impression and guidance of conservation and ornithology organizations like Cornell .

  13. LeeAnn says:

    I an having a terrible time with a pair of crows!! They sis on the box and try to “look in”. This is the first year this had happened. I took away the mal worms thinking that might help, but NOT!!! Help!!!

    1. margaret says:

      Hi, LeeAnn. On Sialis.org nonprofit bluebird site, it does mention crows as a possible predator (less common but possible). See the chart on this page; scroll down to crows. They talk about adding a guard on the entry hole (wood), making sure the box is totally clean by winter’s end so the new nest is way down in the box (not high on past debris), a deeper box…all stuff for the future.

  14. Henry says:

    The old nest may contain eggs of both blowflies and beneficial wasps that prey on blowflies. When you clean out the nest box, it is important to put the old nest nearby in a sheltered spot. The blowfly larva that hatch in the old nest can’t fly and thus can’t return to the nest box to harm the bluebirds. But the parasitic wasps that hatch in the old nest can fly to the new nest to parasitize the next generation of blowflies.

  15. Tracie Evans says:

    Hello I have had for bluebird houses along the edge of my yard approximately 15 feet apart from each other for five years always had bluebirds until last year only one pair of bluebirds, been invaded with tree swallows. So my current question is – it’s April 18th in upstate New York my pair of blue birds have taken residency for approximately four or five weeks. Sadly within the last week tree swallows has taken over. I watch the bluebirds defending the tree swallows for a good week but now I realize they may have lost the battle? haven’t seen the bluebirds for 2 days I now realize my pairing is incorrect, bluebird hses are 15 feet apart side-by-side. Can I move the tree swallows original House so they are BACK TO BACK rather than side to side? Or is it too late in the season? I’m so sad that the tree sparrows have taken over the bluebirds I also have never remove the nests and I’m assuming it’s too late in the year to do that?

  16. Laurie says:

    I and my bluebird family have become another sad statistic. Two years ago my husband and I moved to a rural part of central Florida, on 3.5 acres. I’d never seen a bluebird before we moved out here and after discovering them and talking to some neighbors, I was determined to put up houses, which I did in December. My bluebird houses are on 8 foot metal poles, that are maybe 1.5″ in diameter (like metal conduit). By February we had a nesting pair and several weeks later to my absolute delight we had hatchlings. This past weekend I found a yellow rat snake under some Spanish moss about 20 yards from the bird house. I relocated the snake, and then an hour later my dogs found another one, which I also relocated. I thought I’d done my part but the next morning I noticed no activity at the bird house, which had been busy with the parents flying to and from with insects, and upon inspection I found the worst had happened – a yellow rat snake got inside. All the hatchlings had been eaten. I’m embarrassed to even write this, because I feel like I completely failed these birds. I saw mom and dad later, who came back to check on the nest and it brought me to tears. I should have done more research, and/or relocated the snakes MUCH farther away than what I did. Or maybe it was the same snake that made its way back, but this is Florida so I’m sure there’s more than one snake out there. I got my husband to remove the snake from the bird house and this time I took him miles from here, as I’ve read they can remember where they find food. That said, I know there will be more.

    I don’t know if mom and did will come back or if any bluebirds at all will rebuild a nest there.
    I’ve been sick to death for two days now, and I’ve been pouring through the internet on ways to prevent this and I’ve seen everything from baffles to mothballs to netting. None of it seems fool proof or ideal but the netting seems to be the best for preventing snakes from reaching the nest. The problem (for me at least) is that it almost always harms the snake. I’m one of those weirdos who isn’t afraid of snakes and actually didn’t mind picking up and moving the ones that I found (I know rat snakes are pretty docile when it comes to humans) so I’m not 100% onboard with putting up something that’s going to harm them, but it almost seems like that’s the only option. Any advice that anyone might have on deterring snakes specifically is truly welcome.

    1. Amanda says:

      Well, I’m sitting here looking up info as well, and I just read your story about the snakes. I have one box with five eggs, and I read the snakes can kill the momma bird while she is sitting on her eggs and then eat the eggs! I’m so concerned. I wish you’d get a reply.

    2. margaret says:

      I’m sorry for what happened, Laurie. The best information about protecting bluebirds from predators is on the Sialis website as mentioned in the story, and on this page of that site there is detail about how to make a baffle geared to deterring snakes, which has to do with insuring there is space between the pole holding up the works and the rim of the baffle (and which baffles don’t work for snakes).
      Never, ever use mothballs in an off-label way — they are toxic poison and not meant to be introduced into the environment; the label says so and they are seriously bad news. More on that here.
      Also know that despite our best efforts (like my neighbor’s) in protecting “her” bluebirds, nature is bigger than us and forces at work may not do what we want.

      1. Laurie Anne Thompson says:

        Thank you Margaret, this was really helpful. I’m thrilled to share that we have a new family and five baby birds that are now about five days old. I ordered a baffle and did a little dance … thanks for that tip, too =)

        I just posted another question without realizing I could just respond here, Sorry … now I’m just worried about the Florida heat (and still worried about the snakes of course).

  17. Annie says:

    Hello. We have recently moved into a house with a bluebird house in the backyard. It appears to have been here for quite a while… the roof of the house has caved in, but tonight I saw a bluebird sitting atop the house. Can we repair the roof now or will it scare the bluebird family away?

  18. Laurie Anne Thompson says:

    I notice in your photos that your nest boxes are in full sun. We live in Florida and have a family with 5 hatchlings about five days old. It’s going to be in the lower 90s (at least) for the next few weeks and I’m worried that it’s going to be too hot inside the wooden box. It’s got small vents under the roof and a copper panel on top, but I’m not sure that’s enough.

    How do you combat the heat (if it’s a problem in NY) and should I be concerned?

  19. L. Hester says:

    I live on the coast of Georgia, and we’ve had bluebirds occupy our nestbox this summer with good success. I have noticed recently that the small lizards (anoles) that live around our house (by the hundreds!) have been climbing up the metal pole to the box. I’m wondering if they would be considered predators.

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